


Do I Want to Know

by Aberrated



Category: Undertale (Video Game)
Genre: Drug Use, M/M, Marijuana, Sensitive bones, Sibling Incest, Undertale/Underswap Crossover
Language: English
Status: In-Progress
Published: 2016-03-26
Updated: 2016-03-26
Packaged: 2018-05-29 04:59:04
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 11,874
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6360316
Author URL: https://archiveofourown.org/users/Aberrated/pseuds/Aberrated
Summary: <blockquote class="userstuff">
              <p>Underswap!Papyrus and Undertale!Sans discuss their brothers and come to the conclusion that they may be suffering from the same affliction.</p>
            </blockquote>





	1. Chapter 1

“Give me another hit, would you?”

The Other Sans handed Papyrus the joint and he took it gingerly with his index and thumb, put it between his teeth, and inhaled slowly. Wisps of smoke furled out of the small gaps to either side of his smile, little ribbons twisting and dispersing in the air.

The Other Sans pressed a hand to Papyrus's face. “Don't waste it, man.”

Papyrus smiled and held his own hand to the other side of his face as he finished inhaling the smoke into non-existent lungs. The familiar burn from the joint traced its way down his throat and into his ribcage, filling and expanding until it felt as though he held a crackling fire in his chest, a pressure that wanted to escape. He passed the joint back, still holding his breath, and watched as the Other Sans took another hit, eyes half-lidded, knees drawn up to his chest with his chin resting on them. They both sat on Papyrus's bed, which was devoid of everything but a pillow, a sheet, and a few wrappers from various snack foods that had been consumed at one point or another. If Papyrus wasn't too lazy to check, he wouldn't surprised if most of them were expired.

The rest of the room was much the same – scattered with random piles of trash and clothes that he couldn't be bothered to pick up and organize. Papyrus had visited Other Sans's room once as well, and found that it was practically identical to his own. The Other Papyrus's, on the other hand, had resembled his brother's instead. At first it had been unsettling, seeing a near-carbon-copy of himself walking around and talking in a manner similar to his Sans about puzzles, humans, and traps and being generally energetic. Honestly, it exhausted him to think about just how much effort that sort of personality must take. But after a while he had grown used to it. And his Sans seemed to really get along with the Other Papyrus. It had prompted him to try and get along with the Other Sans... As long as hanging out didn't require doing too much. And when the Other Sans had produced a bag of weed with a wink, Papyrus decided being friends might not be difficult after all.

It had been two smoking sessions since then, and Papyrus had already determined that Other Sans was the best smoking buddy he'd ever had. He was chill, had similar tastes in music, and didn't talk too much, though when he did it was entertaining. He also spontaneously napped, which made it easy for Papyrus to doze off as well.

Papyrus's gaze returned to the Other Sans, who was staring blankly into the distance with the joint in his mouth. He really did look like his Sans, but he didn't have that underlying natural burst of energy humming just beneath the surface, and he wasn't at all dressed in a similar manner. His blue sweater and basketball shorts more closely resembled Papyrus's own outfit, and there was fatigue hidden in the corners of his eyes that Papyrus recognized from his own reflection. Papyrus tucked his hands into the central pocket of his orange hoodie, leaned back against the wall, and exhaled, finally relieving the pressure that had built in his chest. The smoke wafted out in a plume, filling the room and curling around the light fixture on the ceiling. It was just starting to hit him, and hard – beginning from the very top of his skull and trickling down his spine, filling him with a heavy weighted sensation. A small bubble of laughter built in his throat, and he couldn't stop a small, “Heh,” from escaping. Other Sans looked at him.

“That... is good stuff,” Papyrus said.

Other Sans nodded and finished off the joint, grinding the remaining end into an ash tray next to Papyrus's mattress. Then he flopped back, head and shoulders propped on a pillow. “Would you believe I got it from Grillby?”

Papyrus laughed. “Grillby? Really...?”

Sans nodded, grinning. “Guy can't smoke it himself. It goes up in flames the moment he tries. A real _drag_ , if you know what I mean. He makes a nice profit selling it, though.”

Papyrus snorted and shook his head from side to side. “You're just as bad as my brother with the puns...”

“I'm just getting started!” Sans said, “For a guy made of fire, he sure doesn't know how to get _lit_.”

Papyrus groaned, but he was smiling nevertheless.

Sans chuckled. “Turns out a dried plant is no _match_ for him.”

“That must really _burn_ him up,” Papyrus said, and shook his head, “Ugh... now you have me doing it.”

Sans's smile widened. “It completely sets him _ablaze_!”

They dissolved into helpless giggles.

“...w-wait, wait. I've got one,” Sans said, grinning up at the ceiling. Papyrus waited, blinking blearily at him.

Finally Sans frowned. He turned to Papyrus and said, in a very serious tone, “I forgot what I was going to say.”

Papyrus burst out laughing. He slid down until he was lying flat next to Sans, a hand pressed to his forehead and his shoulders shaking. “You f-forgot...”

“No, what was I going to say...? It was really good!”

Papyrus turned to look at him, trying and failing to stifle his snickering. Sans was staring at the ceiling, eyes narrowed in concentration.

“I am very high right now,” he said thoughtfully.

“Is that what you were going to say?” Papyrus asked.

Sans frowned and turned to Papyrus. “...yes?”

Papyrus smiled lazily. “Sans would be so mad at me right now...”

“...hm? Oh...right. The...other Sans,” Sans nodded slowly, “Pap wouldn't be happy either... He doesn't like when I smoke. Says it makes me even lazier than I already am.”

“Is that even possible...?” Papyrus asked.

“I don't even know...” Sans said.

A comfortable silence settled between them. Papyrus found himself making patterns on the ceiling with his eyes. At some point Sans raised his hand up straight out above them and started slowly waving it back and forth, then moving each finger individually as if he were pressing buttons in the air. Papyrus found himself oddly fascinated by it, and watched for some time.

As the waving hand came closer to him he reached out and gently took Sans's hand in his, pulling it close to his face to examine it, noting that it was smaller than his own. He began to meticulously trace each of the digits with the index finger of his other hand, beginning with the pinky's distal phalange and following it down, pausing at the base of each metacarpal before skipping over to the next. The ridges in the joints of the fingers created little bumps along the path he traced. He smiled inexplicably each time his index finger reached the end of one of Sans's, and tapped the end of each before tracing back down.

“...You really do look so much like him,” he said softly. He glanced over to find Sans looking at him, arm pulled across his body, watching his face intently. Papyrus released the hand, but it was a moment before Sans withdrew it.

Papyrus blinked, then looked away. That stare was mildly disconcerting.

Sans heaved a sigh. “My brother is so cool.”

“Yeah...” Papyrus grinned, “Mine, too.”

“...His fences are terrible, though.”

Papyrus laughed. “But his puzzles are good.”

“Very good,” Sans agreed.

“They seem to get along well, don't they?”

“Yeah...I'm glad he has another friend...”

Papyrus turned on his side, facing Sans completely. “It will be harder to be lazy with the both of them nagging us...”

Sans turned on his side to face him as well and grinned. “We'll just have to put the extra effort in.”

Papyrus raised his eyebrows. “Effort?”

They regarded each other for a moment.

“Nah,” they said in unison. Sans laughed, eyes closing, and Papyrus smiled. The air around him felt thick, and the movement felt sluggish. Sans's breath as he laughed created little puffs of air on Papyrus's face. Papyrus couldn't help thinking how familiar Sans's smile looked, the way the light played across his face, how happy he looked when really smiling. Papyrus was suddenly very aware of how close together they were lying. But he felt too weighed down to move away, and he wasn't sure he wanted to. He was so comfortable, after all.

One part of his mind suggested that he could fall asleep, just like this. He knew Sans wouldn't mind. But another part of him knew he wouldn't. There was some sort of buzz deep down in the pit of his stomach, or wherever a stomach should be. He wasn't quite as relaxed as he'd been before.

When Sans's laughing died down and his eyes opened again, they stayed trained on Papyrus's face. He surveyed him for a long moment.

“You look a lot like my Papyrus, too,” Sans said quietly, “But... different.”

“Hm,” Papyrus said, he tilted his head a little, “How?”

Sans's gaze roved across Papyrus's face, scrutinizing. “Explaining is...difficult.”

Papyrus wasn't certain what prompted his next words.

“Then show me.” He frowned at himself. Wondering what the hell that even meant.

Sans didn't seem to think his statement strange, though. He reached out with the arm he was not lying on, his hand partially open. His fingertips settled on his forehead. Papyrus found his eyes closing a little at the contact.

“...This is the same...” Sans said. Papyrus watched him hazily. Sans seemed to be concentrating very hard. He trailed his hand down and traced the edge of Papyrus's brow and temporal line until the tips of his index and middle fingers settled in between his eyes.

“...This is the same,” he said.

His fingers slowly trailed down the bridge of Papyrus's nose, coming to rest on the tip. Sans was looking at him as though he was conducting a very important investigation. Papyrus smiled at the thought.

“...This is the same,” Sans said. Then his fingers followed the line from the end of Papyrus's nose, underneath his eye, and came to rest on his cheek bone. Sans's hand then spread out and he placed it flat against Papyrus's cheek, his thumb resting next to his nose. Slowly, Sans swiped his thumb underneath Papyrus's eye, across, and back again.

“This is different,” he said. His voice had gone quieter. For some reason Papyrus couldn't look away. Sans's face had become so serious.

“My eyes?” Papyrus asked.

Sans nodded.

“Wh...” Papyrus's voice caught in his throat. He cleared it and tried again, “What about them is different?”

Sans was quiet for a moment. He looked thoughtful and puzzled. For a moment, Papyrus thought to himself, he almost looked like his Sans when was attempting a particularly difficult crossword, and Papyrus smiled again. Unconsciously, he leaned into Sans' touch on his face as he waited for a response.

“They're... more...somber? Maybe...? I don't know.”

Papyrus blinked. He wasn't sure what to make of that. Sans continued to swipe his thumb back and forth underneath Papyrus's eye, a gentle pressure that was beginning to lull Papyrus into something of a trance, sending little pulses of sensation to his head, as if waves were slowly passing over him.

“...I think anyone's eyes would look somber in comparison to your brother's,” Papyrus said, “He seems...very optimistic.”

“He is...” Sans said, and smiled, face brightening. Papyrus felt something warm seep into his chest, and flutter there.

“...what else...?” Papyrus asked, his voice a little low.

Sans's hand trailed down to Papyrus's jaw and rested there, his thumb hovering over Papyrus's mouth. He tapped Papyrus's jaw gingerly with his index finger.

“This is the same...” he said, “But...”

His thumb delicately pressed against Papyrus's mouth, before he raised it again. “This is different.”

“Now that one I know,” Papyrus said, “It's because your brother is always smiling... I don't know how he keeps that up.”

Sans grinned. “Yup. He's pretty great...”

Papyrus chuckled. “If I try to do that even for a moment it exhausts me, see?” he said. To illustrate, he smiled as widely as he could, held it for a second, and released it again as if dropping a heavy object. Sans's face went still and he stared at him.

“Whoa,” Sans said. Papyrus chuckled.

“Dude... that changed your entire face!” Sans said.

“Could you... do that again?” Sans asked. Papyrus raised an eyebrow at him, but shrugged and obliged. The smile felt as though it was splitting his face in half. He wondered how the Other Papyrus managed it constantly.

Sans's brows shot up. “You...You look just like him! That's so weird...”

Papyrus shrugged. “I'm a monster of many talents.”

Sans's thumb pressed back against Papyrus's mouth, and Papyrus's smile faltered a little in surprise. The thumb began tracing along the ridges of Papyrus's teeth, and Papyrus's breath caught in his throat. His mouth was a little sensitive, and the weed in his system amplified every touch. The rubbing of Sans's thumb on his teeth was sending more little pulses to his head, but instead of them staying in his skull they began traveling down his spine to his torso, and his chest tightened as though it was being squeezed externally.

Without meaning to, Papyrus's eyes had closed. He exhaled a little shakily, mouth parting a little.

The sound of Sans inhaling sharply made him open his eyes and blink as he tried to focus, smile returning to its normal comfortable size. Sans's gaze was boring into him, pupils bright. As Papyrus focused on him, Sans shook his head a little and withdrew his hand from Papyrus's face. Papyrus couldn't suppress a small sense of disappointment for some reason.

“Sor...” Sans began, eyes a little wide, then paused and smiled. It looked a little forced.

“S-so,” Sans said, “How do I... Look like _your_ brother...? Or not?”

Papyrus considered this for a moment, regarding Sans's features. He had been right, there was something different about them from his own Sans. But it was harder to pinpoint than he expected.

“Well,” Papyrus said, “I think, maybe...It's a little similar to the differences between your brother and me...”

“You mean his perpetual sense of optimism?” Sans said.

“Probably...”

“Does optimism not shine upon my features?” Sans asked, winking.

Papyrus smirked. “No more than mine.”

“Wh...” Sans began, “Where does optimism show up, then..?”

Something, a very small something, in the back of Papyrus's head was telling him that he was treading dangerous ground. But the rest of his mind was too hazy to listen.

Papyrus reached out and rested his hand on Sans's cheek, a near-mirror image of what Sans had done to him a moment ago. He gently pressed his thumb into the corner of Sans's mouth.

“Here, definitely,” he said, his voice softer than he intended. Papyrus dragged his thumb up, to just beneath Sans's eye, both of which stayed fixed on Papyrus's face.

“And here,” Papyrus said.

“So...” Sans said, “Neither of us is very optimistic.”

Papyrus smiled, then took Sans's chin his his hand and gently turned Sans's head side to side. Sans grinned, perplexed, but let his head be manipulated back and forth. Papyrus couldn't help feeling that there was something else that was off.

“It's not just the optimism, though,” Papyrus replied, somewhat introspectively, “I think it's what you're wearing, too.”

He leaned forward and peered at Sans's face. The distance between them shrunk rapidly. Through Papyrus's haze, he noted Sans's eyes widened a little, but that he didn't move away. Then it came to him.

“My Sans always wears a scarf! I don't normally get to see his neck...” Papyrus said, and moved his hand down to lightly rest upon three of the cervical vertebrae just below Sans's skull. He smiled, pleased with himself, and looked at Sans with something akin to triumph.

“I'm pretty sure if we weren't high you would have figured that out a lot sooner,” Sans remarked.

“Hey, you forgot a pun earlier... I think...” Papyrus muttered. Distractedly, he traced a small circle with his index finger on one of Sans's vertebrae. Sans's eye twitched a little.

“You...” Sans cleared his throat, “You forgot what your brother wears every day. That's not the same thing.”

“Hmph...” Papyrus said, and drew his fingers down the side of Sans's vertebrae to where his clavicle met the top of his sternum, peeking through the collar of his shirt.

“I don't normally get to see these either...” Papyrus said, dragging his eyes away and meeting Sans's gaze again. Sans was staring at him intently. His pupils seemed larger than before. Or maybe that was just because he was closer to his face.

Papyrus thoughts stopped in their tracks. Come to think of it, why _was_ he only a few inches from Sans's face?

Sans shuddered visibly. Papyrus tilted his head to the side, perplexed by the sudden movement.

“Your...your hand,” Sans said, voice faltering.

“My hand,” Papyrus repeated.

Sans swallowed. “It's, uh. It's...” He trailed off. He didn't seem to want to finish his sentence.

Papyrus frowned, “A hand?” he asked. He didn't feel very good at guessing games at the moment. In fact, it felt entirely too difficult to try to answer simple questions given the state his mind was in.

“...it's...” Sans tried again. And again, he stopped.

“Like your brother's?” Papyrus suggested. There – that was a better guess, he thought to himself. That was what they had been talking about, after all.

Papyrus watched with mild fascination as Sans's eyes widened and his pupils dilated. He wondered if he had gotten it right.

“...Still on my neck,” Sans said finally, voice a hoarse whisper.

Papyrus glanced down. His hand had partially closed around Sans's shoulder where it met his neck, and his thumb was stroking the cervical vertebra just above Sans's sternum. Papyrus watched his thumb move up and down over them, as though it had a mind of its own. The knobby end of his thumb's distal phalange clicked each time it passed over the small crevices in between each bone. Papyrus wondered if his Sans's neck looked and felt like this, the bone pale and solid beneath his touch.

“Oh,” Papyrus agreed, looking back up at Sans's face, “So it is.”

His thumb continued to caress the vertebra.

Sans swallowed again, audibly. His eyes never strayed from Papyrus's. His breathing was uneven and shallow. Papyrus found himself mesmerized by the reaction. It was such a little touch, after all. But it seemed to be affecting Sans in a peculiar way. Perhaps his neck was sensitive, Papyrus thought, _Is my Sans's neck this sensitive?_ A smile tugged at the corners of his mouth. If he pulled off the scarf and blew on his Sans's neck, would he be flustered, or laugh? He would probably just get mad at Papyrus for messing up his outfit.

Curious, Papyrus leaned forward and blew lightly on the Other Sans's neck, keeping his gaze on Sans's face, to see if it would have a similar effect as his thumb on the vertebrae. Sans jolted and inhaled sharply through his nose, blinking rapidly. Papyrus liked that reaction even better.

Sans's brows drew up and together and he stared at Papyrus.

Belatedly, Papyrus realized what Sans had said earlier might have been some sort of hint to remove his hand.

He did so now, as though releasing a burning pan.

“Sorry...” Papyrus murmured, retracting his hand and stuffing it into the main pocket of his hoodie. He wasn't certain what had compelled him to do that.

Sans didn't reply. His chest was rising and falling rapidly, and he was wearing an odd expression Papyrus couldn't quite identify. Papyrus looked away. His temples felt feverish and his torso constricted for a moment.

“Sorry,” Papyrus said again, “That was weird...wasn't it...?”

Sans was silent for a moment.

“N..” his voice wavered, “...No, it was fine.”

Papyrus smiled wistfully.

“...It's...just...” Sans said. His tone was barely above a whisper.

Papyrus's eyes snapped back to Sans's face.

“...Just?” Papyrus asked, his tone matching Sans's in volume.

“...You...” Sans said, hushed.

Papyrus leaned forward to hear him better.

“...you...” Sans said again, and the sheet rustled as he shifted forward, too, as if he were sharing a secret.

“...I...?” Papyrus prompted. They were so close he could see faint, thin, arcing lines, like sections of concentric circles in Sans's pupils that were even brighter than the area surrounding them.

“...you look...” Sans's words were barely audible. “...so much like...”

Papyrus inclined his head slightly. He could feel Sans's warm breath on his face. The words came unbidden to him and were out before the tiny voice screaming in the back of his mind could stop them.

“...like your broth-”

Papyrus was cut off as Sans swiftly closed the gap between them and pressed his mouth to Papyrus's. His hands snaked upward and gripped either side of Papyrus's face, palms flat on his cheeks. A vague thought passed through his mind – _That guess I got right..._ before everything went blank, and all he could focus on was the three points of contact between him and the monster holding his face captive.

Sans's teeth parted against his own and Papyrus felt the tip of Sans's tongue, impossibly hot, flit out and run along the seam of his mouth, leaving it tingling in its wake. Papyrus inhaled sharply through his nose, startled. His hands spasmed in his pocket. Sans's grip kept him stuck fast as he grazed Papyrus's mouth again. The tingling spread to the rest of his face and he could feel his cheeks heating beneath Sans's palms. San's tongue withdrew briefly, a reprieve that almost gave Papyrus enough time for his muddled thoughts to form into something cohesive, before returning to press more insistently against Papyrus's teeth, burning, demanding.

Papyrus gasped at the sensation, mouth opening slightly. Sans's tongue darted inside his mouth and slid eagerly against his, and Papyrus could taste him. Suddenly his head was reeling, the taste overwhelming his senses. Underneath the traces of weed and smoke and burnt paper there was something else, something sweet and sharp that he found he desperately needed more of. Something familiar.

Heat shot down his spine and ignited a spark of physical urgency within him. Papyrus ripped his hands out of his pocket and snatched at the front of Sans's shirt, burying his fingers in the cloth. He yanked him close enough that he could feel heat radiating from Sans's chest and his knees bumped Sans's shins.

Sans squirmed and let out a choked sound, his grip tightening. He hadn't stopped his kissing onslaught for a moment, but there was a short lull when Papyrus dragged him closer that Papyrus took advantage of. He slid his tongue fervently against Sans's, gradually amping up the intensity. Sans released Papyrus's face and scrabbled at his shoulders, wrapped his arms around his neck, and grasped at his clothes so hard his knuckles scraped Papyrus's shoulder blades.

Papyrus relinquished his hold on Sans's shirt and entwined his arms around him as well, pulling their bodies flush against each other, one hand on the back of Sans's head, helping him to gain control of the kiss. Sans wasn't making it easy for him, but he was beginning to lose ground. His chest was heaving with the effort.

Finally, Papyrus managed to push Sans's tongue back and slip his own into the wet heat of Sans's mouth. The sweet taste from before flared tenfold, and Papyrus couldn't keep a broken rasping moan from escaping the back of his throat. Avidly, he probed San's mouth with his tongue while Sans twisted in his arms and clutched at his hoodie. Papyrus swiped his tongue over the back of Sans's teeth, the roof of his mouth, and across his tongue, determined to taste him completely. Sans shuddered violently and whimpered.

Papyrus drew back, and they both gasped and gulped for air. He exhaled shakily and opened his eyes to see Sans watching him, eyes half-lidded and unfocused, pupils huge and bright. His teeth were glistening.

“...You taste really good,” Papyrus whispered fuzzily.

Sans's breath hitched and he lurched forward and to the side, shifting the both of them so that Papyrus rolled onto his back and Sans landed on top of him with a _whump!_ , knocking the air from his lungs. Papyrus yelped in surprise. Sans's face hovered just above his own, inches a way, his forearms bracketing either side of Papyrus's head.

Papyrus chuckled breathlessly. Sans gently took Papyrus's chin in his hand and turned his face to the side, then slowly licked a stripe down his neck. Papyrus shivered, his laugh stuttering and turning into a moan. Then Sans fastened his mouth over one of the vertebrae and sucked.

Papyrus jolted, breath hissing through clenched teeth. “Shit-!”

A tension that had been building at the base of his spine was now unfurling into his pelvis, making it hyper-sensitive to every little brush of fabric, every movement on top of him. He slid his hands down Sans's back, feeling his ribs and the gaps in between, listening to the catches in Sans's breathing increase in frequency as his hands wandered further downward.

Sans continued sucking on Papyrus's neck, which was sending waves of pulsing energy straight down his spine. Papyrus grimaced, desire burning its way through his limbs. His hands, straying to Sans's hips, spasmed and he gripped them hard. Sans's mouth withdrew from Papyrus's neck and he expelled his breath unsteadily. He drew back a little to look Papyrus in the eyes. There was something ravenous in his expression.

Papyrus kept his gaze fixed on Sans's face as he slid one leg up in between Sans's and guided his hips down. Sans's pelvis collided with Papyrus's femur and his eyes closed, brows drawing together.

“Nn...F..fuck...!” Sans's forehead dropped until it was touching Papyrus's, eyelids screwed shut.

Papyrus smiled and brought Sans's hips down again, a little harder this time. Sans's eyes snapped open and he practically crashed his face into Papyrus's in an effort to kiss him. Papyrus pulled Sans's hips down a third time and he began to rock back and forth on his own, thrusting his tongue into Papyrus's mouth. He was making small whimpering noises in time with the thrust of his hips. Papyrus listened as any remaining shreds of Sans's composure fell apart.

Sans stopped kissing him, drawing back a little, his eyes drifting closed again as he lost himself in the rhythm. Papyrus watched his face, unable to look away, as a very faint blue tinge spread across his cheeks.

The sounds Sans was making were getting louder and more needy. Papyrus's hips were twitching involuntarily, fingers digging into Sans's ilia crests through his shorts, teeth gritting. Sans's eyes cracked open and he gazed at Papyrus through hooded lids, then blinked, coming out of his trance. He leaned over, propping himself with one hand and reached down with the other, fingers ghosting over Papyrus's ribcage, then spine, until he reached the waistband of his pants. Papyrus froze, his entire body taut and anticipating.

Sans's hand slipped inside his pants and rested lightly on Papyrus's pelvis and his nerves sang.

He wasn't sure what kind of face he had made, nor if he'd made a sound or not, but the next moment he could recall was Sans's hand stroking his pelvis in time with his rocking and Papyrus was writhing underneath him. Sans was surveying his reaction with a dangerous glint in his eye, his face even more flushed than it was before. Papyrus shuddered, his entire body vibrating with the built up tension.

Sans's hand hit a particularly sensitive area of Papyrus's pelvis. “Oh...” Papyrus whispered, eyelids fluttering. Sans moaned and kissed him briefly. They moved in tandem, the pressure building and building.

Then Sans began calling his name. It started off as a murmur, and grew until the desperation in his voice was clear.

“...Papyrus... Papyrus...!”

Their movements picked up speed, Sans was pressing so hard on his leg that it was starting to hurt. Papyrus was completely preoccupied by the way Sans's hand felt, and he thrust his hips forward, grinding desperately against it.

“B-bro...!”

Papyrus's eyes widened and snapped to Sans's face. Sans's eyes were glazed over and barely open, yet still they stayed trained on his. Papyrus's orgasm was rapidly building at the base of his spine, multiplying with each stroke of Sans's hand on his pelvis.

“...Papy...” Sans whispered. And for an instant agonizingly beautiful second, Papyrus saw Sans, _his_ Sans. His precious one-of-a-kind Sans in his arms touching him and calling out his name.

Starbursts exploded in his vision as Papyrus came harder than he ever had in his life.

 

______________________________

 

When the world returned from wherever it had gone, Papyrus could feel Sans shaking as his release finished coursing through him. Dazed and still glowing with the after-effects, he opened his eyes and the room swam into focus. Sans slowly raised his head from where it had dropped onto Papyrus's shoulder, face flushed and chest heaving as he tried to regain his breath.

Their eyes met and reality smashed into Papyrus like a tidal wave, cold and unforgiving. The color drained from Sans's face and they simultaneously pushed off one another, Sans rolling away and Papyrus sitting up with a start. He shifted until he sat at the far end of the mattress, clutching at his chest and staring at the floor as he tried to comprehend what had just happened.

The relaxing haze from before had vanished and was replaced with a mind-numbing racing hum. The voice that had been confined to a corner in his head was now repeating something over and over, buzzing and and overlapping, until it resolved and rang clearly in Papyrus's mind:

He'd just had sex with a monster who was practically physically identical to his brother.

The weight of it hit him like a sledge hammer to the gut and he doubled over, one hand clapped over his mouth as though he'd said it aloud. The thought continued to reverberate in his skull. He struggled to draw in air as though a vice was clamped around his ribs, preventing them from expanding.

There was a small sound behind him and he jerked, startled. He turned to see Sans huddled on the edge of the bed, faced away from him.

“...c...” Sans whispered, tone tremulous, “...c-can we pretend...that didn't happen?”

Papyrus froze, eyes fixed on the back of Sans's head, mind racing as he tried to think of a response. Even though Sans's back was to him, Papyrus could see that he was trembling. Papyrus swallowed and his jaw worked as he tried to speak, but no words were coming out. The silence stretched between them, deafening.

Slowly, Sans turned his head and looked at him out of the corner of his eye. His expression was neutral, but his jaw was clenched a little too tightly and his eyes were a little too wide.

 _Take control of the situation_ , he thought to himself. Papyrus tried to smile but it ended up feeling more like a grimace.

“M-maybe,” Papyrus said, voice cracking, “Instead... we could chalk it up to being high and horny and making poor decisions?”

He tried to believe it himself – he'd certainly slept with people while under the influence of one thing or another in the past and ended up regretting it the following morning.

The voice in his head spoke, _But not people who looked like-_

Papyrus viciously crushed the thought before it could finish.

Sans smiled, but it didn't reach his eyes. “Yeah...” he said, “Sure.”

Papyrus could tell Sans wasn't buying that excuse either, not even for a moment. The grin died on his face and he averted his gaze. _No denying it then_. A wall within him crumbled into dust and he buried his face in his hands.

Papyrus had spent a long time trying to refute that he was in love with his brother. Telling himself that it was purely familial. That when his Sans hugged him, kissing the top of his head was an impulse of brotherly endearment, and if he lingered too long it was only because he hadn't yet been released from the embrace. That when other monsters expressed romantic interest in his Sans the flare of anger he felt was protective brotherly instinct, not jealousy. That if he watched Sans eat and his eyes remained on his brother's face for too long, it was only because he was pleased his brother was enjoying his favorite foods, and had nothing to do with the way Sans's eyes rolled up and fluttered closed in bliss as he savored each morsel. That if Sans fell asleep with his head on Papyrus's shoulder while they sat in front of the television, watching his chest gently rise and fall for over an hour was just because there was nothing good on, not because he would rather watch Sans's peaceful sleeping form more than anything else in the world.

After a while, though, it became clear to him that what he was feeling was not how most monsters felt about their brothers, and not the way he should be feeling about his. So every time he caught his hand dawdling too long on Sans's arm or shoulder, or his thoughts straying to the small gap that would appear between Sans's shirt and his pants when he stretched his arms above his head, Papyrus would clamp down hard on the urge to do anything that even remotely surpassed typical fraternal affection. He became very good at reigning in his desire. And if he needed to relieve any sexual frustration, his fantasies very intentionally excluded anything similar to his brother's visage.

Until now that is.

And from the way Other Sans had been looking at him and calling his name, Papyrus was certain he hadn't been the monster Sans had really been thinking of, either.

Papyrus sighed and dropped his hands to his lap, tucking them in his pocket.

“So,” he said, “You too, huh?”

Sans was quiet for a long moment before responding. But when he did, there was no hesitation in his voice.

“Yes.”

Papyrus didn't look at him as he asked, “You know what I'm talking about?”

“Yes.”

There was a pause. Papyrus stared blankly at the wall.

“For how long?” Papyrus said.

“A long, long time,” Sans said, “You?”

Papyrus shook his head, though he didn't know if Sans could see it. “Too long.”

Papyrus could hear the sheet rustle as Sans shifted on the bed.

“How long is too long?” Sans asked.

Papyrus winced and turned. Sans was regarding him levelly. There was no sign of disgust or animosity in his expression. He was simply listening. Papyrus considered his question before responding.

“Years,” he said softly.

Sans nodded slowly. “Same,” he said.

“And he doesn't-?”

“No!” Sans interrupted, flinging his hand out as though stopping something in midair, and Papyrus jumped at the sudden increase in volume. “...No, he doesn't know.”

They observed each other for a long moment. The terror that had gripped Papyrus was ebbing, replaced with a strange sense of relief in his admission, in knowing that someone else understood. That he wasn't alone.

But the tiny voice in his mind was still screaming at him. He had been so good until now. He had been so good at controlling his desires. So good at keeping the images of his Sans in his mind innocent, keeping them brotherly. One moment had completely undone all of that.

Papyrus slumped. The grip around his soul remained firmly in place and it squeezed hard, driving the breath from him, making him wheeze.

“...This was a mistake,” he whispered.

Sans propped his head in his hands and rubbed his temples. “...I know.”

“Got any weed left?”

Sans dug into his pocket and held up the small plastic bag. “Yep.”

“Roll me another one.”

 


	2. Chapter 2

“...Papyrus...?”

Papyrus was floating in a nebulous cloud of semi-consciousness. He was vaguely aware that someone someplace very far away was calling his name, but it was dark and he was warm and comfortable, so he chose to ignore it.

“...Papyrus? Papyrus...” The voice was growing louder and more persistent. Papyrus frowned and wondered if it would go away if he waited long enough without moving. He felt as though he was cocooned, all of his limbs folded and tucked into a cozy ball.

_I could stay like this forever..._

“PAPYRUS!” the voice shouted right next to his head, jolting him straight out of the blissful depths of sleep.

Papyrus groaned as waking awareness of his surroundings slowly returned to him. He cracked open his eyes to find something orange blocking his field of view. Realizing it was the hood to his sweatshirt, he disentangled his arm from the sheet twisted around his body and raised it to peer out.

Light lanced into his sockets and he squinted to shield them against the sudden brightness. He waited for the world to swim back into focus. When it did, he found that Sans's face was hovering inches from his own.

Papyrus flinched backward in surprise.

Sans beamed. “It's time to get up, sleepy skull! You'll be late to work if you don't start getting ready!” As per usual, he was positively glowing with enthusiasm.

“Nnnerrrhmmm,” Papyrus said as way of reply, and lowered the hood again. For some reason, his reluctance to get out of bed was even greater than usual. He settled further into the bundle of sheets and pillows and sighed happily, intent on sleeping the day away.

Sans wasn't having any of it though. Papyrus frowned as his hood was pulled off of his head completely. “Brother, don't go back to sleep! We have to go man our stations! Recalibrate our human traps! Duty calls. There is no time for shirking.”

Papyrus dragged a pillow over his face in response. Sans grabbed it, trying to pull it from Papyrus's grip. But to no avail.

Sans released the pillow and huffed. “Honestly! You would spend your whole life sleeping if given the choice.”

“Mmmm-hmm,” he agreed, voice muffled.

“By the way, it smells in here! ...Were you smoking last night?”

Smoking...? He vaguely remembered sharing a joint last night with-

Sans grabbed the pillow again and yanked, whisking it away. Papyrus was left gazing at Sans's disapproving glare.

“I should have known! You're always even lazier the next morning. Come _on_ , Papy, it's time to get _up_!”

Sans's use of his nickname resounded oddly within his muddled thoughts.

_...Papy..._

His memories of last night, previously submerged in a convenient hazy shroud of sleep and leftover high, surfaced and flooded through his brain. The image of Other Sans, flushed and panting and whimpering while he called Papyrus's name superimposed itself over Papyrus's vision.

He felt as though the floor opened up beneath him and his soul was abruptly doused in ice water. He stared at his brother, suddenly wide awake.

“Papyrus?” Sans said, eyes narrowed in suspicion, “You're not sleeping with your eyes open again, are you?”

Papyrus shook his head as though he could cast the truth from his mind, but it remained steadfastly rooted in place. Sans misinterpreted his shake as a response.

“All right, good. Come on! Let's go! Up, up up!” Sans grabbed Papyrus's arm and tried to drag him out of the bed.

The thought of being around Sans all day while the events of last night played on a loop through his head made Papyrus feel physically ill. He cast around desperately for an excuse to be alone. Papyrus twisted his arm out of San's grip and coughed. “Uh, actually Sans, I'm not feeling so well.”

Sans rounded on him, the disapproval on his face rapidly transforming into concern. “Oh, why didn't you say so?” Sans said, surveying him, “You do look kind of pale...”

“Yeah, uh, I don't know. I woke up feeling a little under the weather, I guess.”

Sans sat back down next to him. “Well if you're not feeling well, perhaps you should stay in bed...”

Papyrus smiled weakly. “Yeah, I'll do that. You go on, I know you have a lot of work to do today. I'll just stay here and get some rest...”

Sans waved his hand as if swatting Papyrus's words aside. “Don't be silly! I wouldn't even dream of leaving my brother if he's sick. I'll stay here and take care of you! I'm sure Alphys won't mind if I take the day off if I explain to her what's going on! Do you have a fever...?”

Sans pulled a glove off and pressed his bare hand to Papyrus's forehead. Papyrus balked. The idea of Sans fussing over him all day was even worse. He shrank away from his brother's touch as though it burned.

“Actually, you know what, bro? I'm fine.” Papyrus said, starting to disentangle himself from his sheets.

“What? But...are you certain?”

Papyrus swung his legs off of the mattress. “Staying in bed won't make me feel better, I probably just need some fresh air,” he said, avoiding looking Sans in the eye.

“...Well, okay. If you're sure,” Sans said.

Papyrus nodded sharply. “Yeah, yeah... I'm sure. Just... give me a minute to get ready, all right?”

“All right. Meet me downstairs when you're ready to go, okay?” Sans said, getting up and walking to the door, “But don't take too long!”

Papyrus looked at Sans, forcing a more convincing smile on his face. Sans grinned back and shut the door, leaving him alone. His smile vanished.

Other Sans had left sometime late the previous night after they had finished getting blazed out of their minds. They hadn't spoken again about what happened, or their admissions. In fact, they'd hardly spoken at all except to say “here” or “thanks” as they passed the joint back and forth. But when he'd left, a strange silent exchange passed between them in the form of a single long look. A mutual understanding. _I won't say anything._

Papyrus sighed and rubbed his eyes hard, soul twinging painfully. He was grateful for Other Sans's discretion, but he couldn't keep the voice in his mind at bay. He couldn't believe he'd done that. How could he have let that happen? He'd seen it unfolding and he just...

Papyrus mentally slapped himself. There was no point in wallowing. He just needed to keep that unfortunate lapse in judgement buried deep within the recesses of his mind, like his desire was before, and make sure it never happened again. No big deal. Soon everything would return to normal. He'd simply take that particular secret to his grave. It certainly wasn't his only one.

He took longer than usual to get ready, actually changing out his clothes for another set, with the exception of his hoodie. Normally he wouldn't bother. He didn't really sweat enough on a regular basis to make it worth switching garments every day. He also took the time to put on his beat-up pair of converse rather than the ratty slippers he regularly shoved his feet into.

Changed, he glanced around, looking for any other mundane preparatory tasks to prevent the inevitable.

_Stop stalling._

Papyrus steeled himself and headed downstairs to where Sans was practically bouncing up and down next to the front door.

“Oh good! You're ready! Let's go, let's go!” Sans said, flinging the front door open so hard it banged off the wall. Papyrus winced. Sans looked as though he was about to charge out the door but stopped and turned back.

“Oh, but...” he said, and reached out and gently touched Papyrus's arm where it protruded from his pocket, “Don't push yourself too hard, okay? Especially if you're not feeling well.”

Papyrus flushed. “I'm fine, Sans.”

“Okay. But still,” Sans said. He hadn't removed his hand. “Let me know if you need anything.”

Papyrus raised an eyebrow at him. “Who's the older brother here?”

Sans snickered. “You are,” he said, and looked up at him, expression fond. As Papyrus met his gaze, his soul fluttered in his chest and his breath caught.

He swallowed and stamped hard on the feeling, chastising himself. He shifted slightly so that Sans's hand dropped from his arm.

“Come on,” Papyrus said, “We'd better get going.”

Sans nodded enthusiastically. “Right!” he said, “There are humans to patrol for!”

They trekked out into the snow, shutting the door firmly behind them.

 

______________________________

 

Sans walked next to Papyrus, his arms swinging and a bounce in his step. The snow was light and fluffy and muffled their footsteps as they passed through Snowdin. Sans greeted every monster they saw with a “good morning!” or “how are you?”, and was cheerful whether he received a reply or not.

Eventually they walked into the woods beyond, which were mostly silent save for the occasional _womph_ of a snowdrift falling to the ground, or the soothing burble of the river in the distance. Papyrus normally found the woods relaxing. But this morning the looming trees with their dark twisting branches were mildly intimidating. The knots in the bark were like eyes watching him.

He started when Sans spoke.

“I've been working on this new puzzle!” Sans said.

“Oh?” Papyrus said. He kept his eyes resolutely fixed on the path ahead of them as they walked. Maybe if he stayed at his guard post all day rather than patrolling with his brother he'd spend most of it alone. Typically Sans stopped by only once or twice to make sure he wasn't shirking before rushing off to another part of the forest.

“It utilizes pulleys and levers! It's quite complex. It requires balancing weights of varying mass in order to cross!”

“That's pretty cool, bro.” Or maybe he could slip away once Sans had left, and spend the rest of the day at home or in Waterfall, at one of his other jobs. Give himself the day to cool off and meticulously repress every unfortunate memory from the previous night.

“I know! Other Papyrus helped me come up with the idea. We've been working on it together.”

“Uh-huh.” Papyrus was only half-listening.

“It's taking some time to implement. We've only just begun the actual construction process! I insisted on calculating all the necessary forces to reach equilibrium within the system ahead of time, and then we had to draw up the blueprints...”

Papyrus nodded as though he was paying attention. If Sans asked him where he had been later, he could just tell him that they had missed each other because he had been out patrolling. That would work.

“...but the friction is making it hard-”

Sans's words jolted Papyrus out of his plans. Papyrus stopped in his tracks and stared at his brother. “What?”

“You know! The model's never perfect. You can't just assume that every pulley is truly frictionless! That works in theory but not in practice,” Sans said. Sans frowned at him. “You know this, Papyrus. You read me that physics book Undyne found at the garbage dump ages ago.”

 _Pulleys. He's talking about the puzzle, you idiot._ Papyrus collected himself and schooled his features into something calmer and cleared his throat. “Just because I read you that book doesn't mean I understood it,” he said.

“Oh!” Sans said, eyes lighting up, “Then I'll explain it to you!”

He held up his hands and pressed his palms together. “When two physical bodies grind against each other-” he started rubbing his hands together to demonstrate. Papyrus's eyes widened, “-there's typically some amount of friction and heat-”

Papyrus inhaled sharply and promptly descended into a coughing fit. Sans jumped and reached for him as though to pat him on the back. Papyrus held up a hand shakily and waved him off as he hacked into the other.

“Sorry,” he said when he finally managed to get it under control.

Sans was looking at him, brows drawn together. “Papyrus, are you sure you're okay? I can still take you home...”

“No, no. I'm fine. Really,” Papyrus said.

“That didn't sound fine...” Sans said, concern evident in his face.

“I am. I'm perfectly fine,” Papyrus said firmly. There was no way he would be able to keep Sans from hovering next to him all day if his brother thought he was sick.

Sans didn't look convinced.

Papyrus decided not to give him a choice. “Come on,” Papyrus said, and started walking off without him. He heard Sans make some sort of noise in protest and then trot to catch up.

“...All right. But if you do that again I'm taking you home,” Sans said.

Papyrus chose not to respond.

The rest of the way to the guard post, Sans continued talking to Papyrus about the puzzle. Papyrus tried to listen but his mind was quite occupied with _not_ thinking about his Sans saying “friction” and “grinding bodies.” In fact, he was so focused on not thinking, he didn't notice when they approached his shoddily-made guard post and walked right past it.

“Uh, Papyrus?” Sans said.

“Hm? Oh.” Papyrus turned back.

Papyrus could feel Sans watching him as he entered the shack and sat down. He leaned forward on the counter and tried to smile at his brother.

“See you later?” Papyrus said.

“Of course! I'll check in on you. Don't push yourself,” Sans said. Papyrus nodded obediently.

 _Please leave,_ he begged silently.

But instead, Sans approached the shack until he was standing on the opposite side of the counter. “You'll tell me if you need to go home, right?”

Papyrus sighed. “ _Yes_ , Sans.”

Sans grinned and shrugged. “Just checking,” he said, “And one more thing.”

He leaned forward and reached towards Papyrus with both hands. Papyrus froze in place as Sans's hands passed by either side of his face. He was uncomfortably close. Though Papyrus's definition of a comfortable distance between himself and his brother was rapidly increasing.

Sans grabbed his hood, tugging it up over his head.

“You don't want to catch a cold, Papy,” Sans said, releasing the hood, “ _If_ you don't have one already.”

Sans smiled and his eyes brightened. As Papyrus gazed into them he felt as though his soul did a somersault in his chest and the smile on his face grew more genuine.

Papyrus shook his head. What was _wrong_ with him? _He loves you because you're his brother. Act like it._

“Thanks, Sans,” he said.

“No problem! And here,” he said, reaching up to his bright blue scarf, “You can wear this too...”

Sans began to tug the scarf from his neck and Papyrus caught a glimpse of the cervical vertebrae just below his chin. A thought, unbidden, rose to the surface of his mind. _I know what those feel like..._

Other Sans's expression when Papyrus's hand was on his neck the previous night materialized in front of him. The way he'd shuddered as Papyrus ran his thumb over the vertebrae, and gasped when Papyrus leaned forward and-

He lunged forward. “No, no!” Papyrus said, tucking Sans's scarf back around his neck firmly, “That's okay!”

Sans jumped, clearly startled by Papyrus's sudden burst of energy. “O-okay...?”

“Uh, you don't want to catch one either. You keep it,” Papyrus said, pulling back. He laced his fingers together on the countertop, and clenched them tightly, inwardly scolding himself for touching him at all.

Sans smiled at him and placed one gloved hand over Papyrus's. “You're always looking out for me.”

Papyrus felt as though little dark tendrils were winding around and piercing his soul, constricting and leeching. He struggled to breathe for a moment. Papyrus withdrew his hands from Sans's touch and slipped them back into his pocket, then forced a smile on his face. Sans turned to leave.

“See you later, Pap!” Sans called over his shoulder.

Papyrus mumbled something that sounded like an affirmation in reply and watched as his brother jogged out of the clearing. Once he'd disappeared behind a line of trees, Papyrus let his head fall to the counter with a clunk.

_I'm such an idiot._

He stared at the streaked wood grain of the counter and wondered vaguely if he could sink into it and become one with the table. Maybe even set down roots and grow a couple of leaves, photosynthesize a little. It sounded quite appealing. Tables and trees didn't have to worry about intrusive desires about their brothers, as far as he knew.

He could suppress these thoughts so well before. He used to be able to snuff them out like a glowing ember at the tip of a cigarette before they even developed into vague shapes. Now he had a surround-sound technicolor visual popping into his head every time Sans so much as looked at him.

Papyrus knocked his head against the counter, each knock punctuated with a silent syllable, _I. Am. Such. An. Id. I. Ot._

He sighed wearily. He just needed to give it time to fade away, that was all. Eventually Sans would meet some nice monster who he would fall in love with. It wouldn't be hard. Once everyone realized just how wonderful Sans was, he wouldn't lack for suitors. And perhaps he would decide to live with this new monster, and maybe they would start a family together. And Papyrus would be the cool Uncle who visited occasionally. The inappropriate feelings he kept having would finally recede and disappear, and he would go back to loving Sans the way he was supposed to.

He ignored the way it had become harder to breathe when he imagined not seeing Sans every day, or his brother looking at someone else with adoration. Or embracing someone else. Or kissing them.

His soul twinged and Papyrus raised his head abruptly, frowning. He rubbed his eyes hard and stood, exiting his poor excuse for a guard post. He never did like building things. It took far too much time and effort.

He decided to leave before Sans returned to check on him. Papyrus set off, walking in the opposite direction from where Sans had headed. It took him away from Snowdin, but he figured he could wander some of the less-traveled paths and circle back around in order to slip past Sans undetected.

He scanned the underbrush to either side of the main path until he spotted a gap between two stands of trees that concealed what could almost be described as a trail, and slipped between them. He wasn't entirely sure where it led, but he had a general sense of the direction he should go. The way was overgrown and the snow was thick, and high above the branches of trees creaked if so much as a breeze wafted by, casting swaying dappled shadows on the ground. As his feet carried him further into the forest, his gaze drifted upward, past the canopy, to the “sky” above. Sometimes it was easy to forget that they lived in a giant cavern. The distant ceiling was shrouded in clouds that frequently thickened to create snowfall. But occasionally they parted such that the dark rocky surface of the cave became visible, or swirled around stalactites that were long enough to pass through the oppressive cloud cover.

The underground didn't seem small to him when he was a child. But as he grew older it became more apparent that there were boundaries, limits to their domain. Now, however, alone in the silence of the forest, he wondered if he could keep walking forever, until everything was far behind him. Until all he had to worry about was setting one foot in front of the other.

Papyrus was so busy staring blankly at the clouds he didn't notice a root growing from the ground, mostly buried in snow, until he tripped over it, stumbling into a chest-high thicket. The thorny branches caught on his clothes and tugged, making it difficult to pull back out. Muttering curses to himself, he pushed forward and through it instead, wincing as the barbs bit through his pants and sweater. He reached the other side and extracted himself from the bush, tugging hard to free one of his sleeves from a particularly clingy bramble. Papyrus brushed the snow and nettles from his clothes, frowning, then looked around. He was in another clearing, one that looked vaguely familiar, but he was having trouble placing it in the map of the forest he had in his head.

Then it hit him. He was near the Other Sans and Papyrus's guard stations. In an effort to avoid his Sans's patrol route he had inadvertently wandered straight into their district.

 _Shit, shit, shit._ Seeing either of them was the last thing he needed at the moment. He listened carefully, worried one of them might have heard his ungraceful exit from the bush. But the surrounding forest was silent. He set off again, grateful for the snow muffling his footsteps. If he could just avoid the other two until he could slip past his brother's patrol route and into Snowdin he would be in the clear. No interaction whatsoever.

Papyrus stayed alert, wary for the slightest movement. But still all was silent. He was beginning to wonder if they had taken the day off. But given the Other Papyrus's similarities to his Sans, he highly doubted it. Neither of them were prone to missing. He was about to round a bend in the path when he caught a glimpse of red in the distance.

Papyrus's soul leapt in his chest and he stepped back quickly, inching closer to a nearby tree to better conceal himself. He leaned forward, peering around until he could barely see a sliver of the path ahead. To his dismay, the red was from the Other Papyrus's scarf, who happened to be walking through the forest, and in his direction.

He ducked back. He was fairly certain the Other Papyrus hadn't seen him, but orange was an easy color to spot. Silently cursing his choice of clothing, he pressed his back flat against the tree and waited.

The sound of Other Papyrus's footsteps were faint but slowly growing louder as he approached. Papyrus slowly edged around the tree in the opposite direction, keeping the trunk between himself and the Other Papyrus in order to completely block him from view.

The Other Papyrus passed by without stopping, and Papyrus listened as his footsteps retreated. Papyrus peered around the trunk and watched him disappear behind a line of trees, the red of his scarf periodically flashing in between.

He released a breath he didn't know he had been holding and slumped, tension dissipating. He felt stupid, running and hiding as though he was a child playing hide-and-seek. Though some part of him felt oddly accomplished for avoiding detection. Now he could get back to Snowdin and spend the rest of the day in his room, brooding or sleeping. Or both.

Papyrus stepped out from behind the tree, glancing warily behind him for signs of Other Papyrus returning, and promptly collided with something soft but solid. His head whipped around and fixed on the short monster in front of him.

He had just walked smack into Other Sans, who was looking up at him, clearly taken aback. Papyrus flinched and stepped backward involuntarily.

 _Fuck,_ his brain supplied helpfully.

Never mind, Papyrus thought to himself, the underground was definitely far too small.

Sans blinked at him. "Uh...hi," he said.

 _Just interact with him as you would normally_. Papyrus dipped his head in way of greeting. "Hey."

"What are you...um..." Sans began.

"I was just...patrolling," Papyrus said, "And I, uh... Got a little turned around."

"Oh," Sans said, nodding.

"...Seen anything unusual?" Papyrus asked.

"You mean...humans?" Sans said.

"Yeah."

"Nope, everything here is...normal. You?"

"Nothing to report," Papyrus said.

"Right," Sans said.

Silence stretched between them. Papyrus cringed internally and cast around for a safe conversation topic. Asking after his brother was out of the question. He was pretty sure he had already covered everything he could without straying into dangerous ground, and not very well.

Papyrus tried to think of a polite way to leave without making things even more horribly awkward.

"Well-" he said.

"I should-" said Sans at the same time.

"Sorry," Papyrus said, "Go ahead."

Sans rubbed the back of his neck. "I should catch up with..." He trailed off, gesturing behind Papyrus in the direction Other Papyrus had gone.

"Right," Papyrus said, "And I need to get back."

Sans nodded, gaze averted.

"Okay then. See you," Papyrus said, about to step around him.

"See y-" Sans started to say, looking up.

"Sans! There you are!"

Sans froze, eyes widening minutely, and Papyrus felt the pit of his stomach -- or lack-thereof -- drop. He turned in time to see the Other Papyrus round the stand of trees, a smile on face and waving cheerfully.

"I know you're sluggish this morning because you didn't sleep well but do try to keep up- Oh! Hello other me!" he said as he spotted Papyrus. He trotted closer, joining them, "And how are you today? What brings you to our neck of the woods?"

Papyrus tried to smile. It made his teethe ache. "Oh... Just, you know. Checking in."

The Other Papyrus grinned impossibly wider and clapped him on the back. Papyrus nearly staggered. "How diligent of you! Coordination will certainly make it difficult for any humans to slip past us!"

"Er...yeah. Just what I was thinking," he replied.

"And great minds think alike! Nyeh heh!" the Other Papyrus said, "Sans, the other me and I share brilliant ideas as well as our devilishly good looks!"

Papyrus barely stopped himself from physically recoiling and glanced sidelong at Sans, who was staring fixedly at the ground at their feet. "Mm-hmm," Sans mumbled.

Other Papyrus continued, oblivious, "The four of us make an excellent team. Your Sans and I have had quite the blast on our latest collaborative effort!"

Papyrus felt that familiar crushing grip on his soul at the Other Papyrus's use of _your Sans_. He ignored it and nodded. "Right... He was telling me about it earlier."

"Speaking of, we really should go! We are running late."

 _Oh thank goodness_... "Sounds good. I'll catch you later then," Papyrus said, starting to walk away from the other two, "Good luck on your patrolling.."

"Hm? No, I meant all of us!" The Other Papyrus said, "Your brother said he would bring you by so we could show you and Sans our progress! That's where we are headed now."

Papyrus and Sans spoke at the same time. "He did?" "We are?"

The Other Papyrus quirked an eyebrow at the both of them. "Yes and yes," he said, "Sans, I told you this this morning. So come along! We've been anxious to share it with you!"

 _No, no, no_. Papyrus began to panic, and he swallowed hard.

"Uh... But..." Papyrus said, "That wouldn't leave anyone on patrol duty. I think maybe I should get back to my route and keep an eye out there..."

"Yeah, and I could stay here and keep watch, bro," Sans spoke up, "that way we cover all our bases..."

Other Papyrus planted one hand on his hip and with the other wagged an index finger at the two of them. "As much as I appreciate how responsible you two are, did you really think the Other Sans and I wouldn't have taken that into account? I've already asked Doggo to cover my post and your brother has made similar arrangements. Now come! You're going to love it!" Other Papyrus reached out and grabbed Sans's hand and Papyrus's elbow and began pulling them along.

Papyrus opened his mouth to protest but nothing came out. He glanced at Sans again, who had a strangely blank expression on his face, as though he was trying really hard not to emote, and his gaze was fixed on the hand that his brother held.

Their eyes met behind Other Papyrus's back and they traded a brief look before he whisked the both of them away at a brisk pace.

 _So much for escaping,_ Papyrus thought. He had been successfully blocked at every turn. Today was turning out to be spectacularly frustrating.

 

______________________________

 

The site of the new puzzle was not far, and like his brother, Other Papyrus chatted animatedly the entire way there. Papyrus did his best to focus on his words rather than the sense of dread creeping up the back of his neck that made him want to hunch his shoulders until his head disappeared between them. Papyrus hoped his Sans would not be there when they arrived. Then maybe he could duck away under the pretense of going to look for him.

They reached a large glade in the woods that was divided in half by a trench several feet wide and deep enough that he could not see the bottom of it from where he was standing. A strange wooden contraption resembling a bridge spanned the middle of it, from which numerous ropes stretched to pulleys in the trees above. Various objects that looked as though they were retrieved from the dump were dangling from the ropes acting, Papyrus supposed, as weights for counterbalance. It looked rather like a giant mobile. He stared at it for a moment, dumbstruck.

“Whoa,” he heard Other Sans mutter.

“Isn't it grand?” the Other Papyrus exclaimed, startling Papyrus from his reverie, “I must say, I don't think I could have accomplished this on my own. Your brother really is very skilled at construction!”

“Yeah,” he agreed.

“Papyrus!” Any remaining shred of hope he had of leaving died and Papyrus turned as his brother galloped across the clearing towards the three of them.

“I was wondering where you went! I told you I would check up on you. Where did you go?” his Sans said, skidding to a stop in front of them.

Papyrus shrugged. “I was just patrolling, bro...”

“You really shouldn't be patrolling if you're sick,” his Sans scolded.

“I didn't know you were sick!” the Other Papyrus said, turning to him.

“I'm not sick,” Papyrus said quickly.

“There's no shame in taking time to recuperate, you know,” the Other Papyrus said.

His Sans huffed and crossed his arms over his chest. “That's what I said, but you try telling your older brother what to do.”

Out of the corner of his eye, he saw Other Sans scuff his slippered foot against the ground.

Papyrus flushed, shrinking under their combined scrutiny. “Really, I'm fine.”

His Sans beckoned to him. “Come sit down. There's a few minor tweaks we need to make before we show it to you!”

He allowed his brother to usher him to a log at the edge of the clearing, and sat.

“Stay there,” his Sans said firmly.

“You, too, Sans! We will just be a moment,” Other Papyrus said, one hand on his brother's shoulder as he gently guided him toward the log as well.

Other Sans sat heavily and glanced up briefly to smile at his brother. Other Papyrus grinned back before turning away, and the two older brothers were left to themselves at the edge of the clearing.

Papyrus watched as the smile dropped off of Other Sans's face. The circles under his eyes seemed darker than they had been the previous night, as though he had smudged charcoal beneath them.

 _Did he sleep at all?_ Papyrus wondered. Uneasy, he looked away. He couldn't worry about it. Worrying would lead to asking, and asking would lead to resurrecting a topic he was currently trying to bury. That was the last thing he needed to do. No. It was best to keep quiet.

In the distance, his Sans laughed and gestured emphatically at Other Papyrus as they worked. Papyrus still wasn't entirely sure just what the puzzle was supposed to do. If he listened closely, he could make out words in their conversation drifting over.

“...If we balance the system just _so_ , the human will have to distribute their weight evenly on either side of the bridge after pulling this precise sequence of levers. Otherwise, the system tips and they'll fall straight into the trap waiting below!”

“And once in the trap, they shall be powerless to avoid capture!” Other Papyrus said.

“Exactly!” his Sans said.

“Excellent! ...Although, do you think that...”

“Hm?”

“...Perhaps the puzzle is a bit too difficult?”

“Isn't that the point?”

“Yes, but, maybe... we should put up a sign with some sort of hint ahead of time. Just to give them a sporting chance.”

“I see what you're saying. It would be nigh impossible for a human to overcome this puzzle otherwise,” his Sans agreed, nodding thoughtfully.

“Quite,” the Other Papyrus said. He struck a dramatic pose, “Our puzzles are very intellectually demanding!”

His Sans mirrored the pose. “Even with the sign, no human shall stand a chance!”

“Especially not when the puzzle is designed by both the Great Papyrus...!”

“And the SANSATIONAL Sans!”

Papyrus winced and heard Other Papyrus groan loudly.

“You ruined our perfectly good speech!” the Other Papyrus whined, then rounded on the older brothers, hands planted on his hips. “Sans! This Sans is just as bad as you with the puns! Will I never be free of your atrocious humor?” Other Papyrus shouted.

“If you keep reacting like that, I'm going to start calling you the _Irate_ Papyrus,” his Sans said.

Other Papyrus let out a loud “NYEH” in frustration as his Sans doubled over, giggling. Papyrus felt the corners of his mouth quirk up despite himself. He couldn't help it. His brother was so persistently cheerful, so utterly endearing, that he couldn't help but-

_Stop._

Other Sans was silent. Papyrus had expected him to pun or something in reply and looked at him, confused. He was staring intently at the Other Papyrus, and one of his hands had drifted up to his face, fingertips ghosting over his chin and mouth.

 _Oh._ Papyrus knew that look.

He saw Other Sans's gaze flicker, ever so slightly, towards him, before the hand dropped abruptly to his lap and his gaze turned downcast. A faint furrow appeared between his brows and he leaned forward, just a bit, as though he wanted to curl in on himself.

To anyone else he would look pensive. Perhaps a bit tired. To Papyrus, he looked miserable.

Papyrus's soul ached in sympathy and his resolve weakened. He nudged Other Sans with his elbow. “Hey.”

The shorter skeleton started and turned to him.

The voice in his head shrieked. _You were going to bury it. This isn't burying it._

He ignored it. “You want to talk about it?” he asked quietly.

Other Sans blinked at him. “T...” he whispered.

“Sans! Other me! It's ready!” Other Papyrus called, interrupting them.

“Come and see, you two!” his Sans said.

Papyrus waved at them in acknowledgement, then turned back to Other Sans. He was watching their younger siblings.

“...Yeah,” Other Sans said.

“Come by later.”

Other Sans nodded. “Okay,” he said, eyes on his brother.

 

**Author's Note:**

> Thanks very much to my significant other for beta-ing this for me and convincing me to write it in the first place. I love you, you big enabler.
> 
> The title of the fic is inspired by "Do I Wanna Know" by the Arctic Monkeys.


End file.
